1. Field of the Invention
This invention relates to video signal processing. More particularly, the invention relates to methods of and apparatus for the generation and manipulation of images in three dimensions.
The images so produced may form part of a complete scene which has been simulated by the addition of the images to a background video signal. The resulting complete scene may, for example, be used as the moving display in a simulator, such as a flight simulator; as the moving display in a video game; and also more generally where digital scene simulation is required, such as in film-making.
2. Description of the Prior Art
Hand drawn animated films such as the Disney cartoons have been well known for a long time, but are time-consuming and expensive to produce. Recently, models have also been extensively used in film-making, the models being manipulated frame by frame to achieve the required animation. Again this is time-consuming and expensive.
More recently, so-called digital scene simulation has been used, the object of this technique being to generate frame by frame within a computer, images of animated scenes for video or film. No limitation on the range of scenes is implicit in the technique, although a particular application has been the generation of scenes for science fiction films. A feature of digital scene simulation is the immense amount of data that needs to be stored and processed, and the consequent requirement for very large computational power. For example, Upson suggests in "Large scale digital scene simulation for feature films and commercial productions" presented at Computer FX'84, and published by Online Publications, Pinner, UK, 1984, that for a 2.times.10.sup.7 pixel frame, up to 1.2.times.10.sup.11 computations per frame may be required. The fastest general purpose computer currently available is probably the CRAY XMP which can carry out up to 2.times.10.sup.8 computations per second, so even that computer takes many seconds to produce a single frame. A slower, less expensive computer may well take hours to produce a single frame.
A central problem in digital scene simulation is the generation and manipulation of three-dimensional objects and it is with this problem that the present invention is particularly, but not exclusively, concerned.